Current efforts to improve power system monitoring and event reporting focus upon detecting and correlating data from a number of dispersed sites in the network. To achieve synchronized readings, local data sampling is typically referenced to a time base synched to an absolute time reference, such as can be obtained through the global positioning system (GPS). Measuring devices sample current and voltage values and may perform some analysis on the data, such as harmonic analysis. Typical sampling rates may range from 1 to 12 kHz for high resolution measurements, or 500 times that frequency (e.g. up to 6 Ms/s) for high speed lower-resolution transient detection.
A typical power system measurement device uses separate circuits with different sampling rates in order to accomplish high resolution measurements and high speed transient capture. The use of two circuits introduces complexities for combining the data into a single useful data stream. The gain and aperture match between the two circuits cannot be made perfect.
Typical power system measurement devices low pass filter sampled data to remove noise and other artefacts.
Accuracy, speed and low cost are desirable attributes in developing a power measurement device.
Similar reference numerals may have been used in different figures to denote similar components.